Archive for March, 2014

Concentration Units – In Other Words

By John Brereton, PhD, Vice-President of NJB Soft

Here’s an interesting point of view I put together from some old lecture notes I have…

Most pollutants or contaminants in the water matrix (e.g., wastewater, drinking water, stormwater) are measured in units of milligrams per litre (mg/L), micrograms per litre (ug/L), nanograms per litre (ng/L), or sometimes even picograms per litre (pg/L).   For example, the drinking water Maximum Contaminant Level (MCL) for fluoride is 4.0 mg/L; for arsenic, 10 ug/L; and for dioxin, the MCL is 0.00000003 mg/L, or 30 pg/L.  Have you ever pondered just how tiny these concentration units are?  Let’s take a look from several different perspectives.

Since 1 liter of water (pure water at 4ºC and 1 standard atmosphere pressure) has a mass of 1 kilogram, 1 milligram in 1 liter of water under most conditions is approximately equal to one part per million parts (i.e., 1 mg/(1000 mg/g x 1000 g/kg)).  Similarly, 1 ug/L is analogous to 1 part per billion, 1 ng/L is 1 part per trillion, and 1 pg/L is 1 part per quadrillion.

We can perhaps imagine one dollar in one million dollars, but for most of us, it is difficult to visualize how much money $1 million dollars really is.  Would one million single dollar bills fit in a suitcase?  a closet?  a room?  a house?

Let’s think in terms we may be able to better relate.  In terms of time, one second in a million seconds  is equal to one second in 11.6 days (or one minute in 2 years).  One second in a billion seconds is the same as one second in 31.7 years.  One part per trillion?  That’s the equivalent of 1 second in 31,710 years, and one part per quadrillion is 1 second in 31 million years.

Alternatively, in terms of distance, 1 ppm = 1 millimeter in 1 kilometer (or one inch in 16 miles).  One ppt is equivalent to 1 mm in 1,000,000 km  (or 3 millimeters in the distance between the earth and the moon).

Next time you measure a contaminant concentration of 1 mg/L, that’s analogous to one car in bumper-to bumper traffic from Cleveland to San Francisco.  One ppb or 1 ug/L is like one silver dollar in a roll stretching from Detroit to Salt Lake City, or one sheet in a roll of toilet paper stretching from New York to London.

Gives you some idea of how small these quantities can be.  I don’t mean to say that these measurements are too small to be concerned about.    Just gives you a different perspective on the quantities we deal with every day.

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Safe Drinking Water Act Violation? – You are not alone!

By John Brereton, PhD, Vice-President of NJB Soft

The task of managing drinking water quality for a public water system is challenging.  Given the sheer number and complexities of SDWA regulations, mistakes are understandably common.  In fact, over half (55%) of all Community Water Systems (CWS) had at least one violation of SDWA regulations in 2011, according to a recent paper in Jornal AWWA.  Almost one third of all CWSs had at least one “Monitoring and Reporting” violation (e.g., failure to collect a sample on time).  Of all SDWA violations, 84% were procedural errors (Monitoring and Reporting, Public Notification, and Consumer Confidence Report violations), not health-related (e.g., maximum contaminant limit exceedences).

Does size does matter?  An analysis of the 2011 SDWA violation data reveals that smaller water systems are no more likely than larger systems, except very large systems, to violate health-related requirements, and smaller CWSs appear more likely than larger systems to violate monitoring, reporting, and notification requirements.  For all systems, staying on top of monitoring results and knowing the implications of specific contaminant levels is critical to avoid rule violations.

Violations that are procedural in nature are preventable with improved data management, guidance on compliance monitoring scheduling and more timely responses to results-triggered requirements.  Fortunately, multiple information sources and tools are available to help deal with these challenges.  For guidance on specific rules, check out USEPA’s Compliance Guidance Website.  When reviewing a particular rule, watch for mandatory monitoring frequency changes triggered by certain monitoring results, and be sure to check your State regulations for additional and/or more stringent requirements.

For health related violations, being aware of contaminant levels trending upward allows systems to proactively take steps to improve treatment or operations before an MCL exceedence occurs.   Rule-driven software can be invaluable in exposing water quality trends, alerting sampling deadlines and required changes in monitoring frequency, advising when Public Notification is required, and automatically generating CCRs.

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Clean Water Act Violations – The Numbers are Surprising!

By John Brereton, PhD, Vice-President of NJB Soft

There are roughly 450,000 NPDES permittees, of which 6,700 are major facilities with individual permits, 42,597 smaller facilities with individual permits, and 400,000 permittees operating under general  permits.  Major municipal facilities includes those with design flows of greater than one million gallons per day and facilities with EPA and State approved industrial pretreatment programs.  How many facilities are in non-compliance?  The answer may surprise you.

For example, 55% of major facilities nationwide were in a non-compliance status in the 2009 fiscal year.  Twenty-three percent of major facilities were in “significant non-compliance”.  Facilities are in non-compliance if they have had effluent violations, compliance schedule violations, permit schedule violations, single event violations (for example, violations found during inspections), or reporting violations (such as failure to report) during the fiscal year.  Facilities can be in significant non-compliance because they repeatedly exceed the effluent limits in their permits, they fail to report, or they violate compliance schedules.

The ECHO State Comparative Maps website provide a quick interactive way to review national trends and compare states and territories.  It covers Air and Hazardous Waste topics in addition to NPDES programs.  The maps display individual state data in a number of categories, including facilities in non-compliance, facilities in significant non-compliance, facilities with effluent violations, facilities with single event violations, and facilities reviewed with serious violations.  Select a category, select a year (currently between 2009 and 2013) and click on a state to see a summary of reported statistics.  Here are a few results from 2012:


Percentage   of Major Facilities in


Percentage   of Major Facilities in

Significant   Non-compliance














EPA provides various summaries of regulation and permit violation and enforcement data on the web.  For more information, go to EPA Annual Reports.

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